To safely operate a wind turbine, a control system may determine a current state of the wind turbine and identify whether the state is within an operational envelope. Based on measured sensor data, the control system may calculate the current state of the turbine in a multi-dimensional space where each axis of the multi-dimensional space correlates to one of the measured parameters. The boundary of the operational envelope may define a region of the multi-dimensional space where the wind turbine is behaving in a safe manner. A safety system may determine if the state determined by the control system is accurate. If so, the safety system determines whether the current state is within the operational envelope. If the state is outside the envelope, the wind turbine may switch to a safe state during which the turbine may be decoupled from the utility grid or the rotor is stopped.